Diesel engines are used in a wide variety of industrial applications. These engines are known as compression ignition engines because they are internal combustion engines that utilize the heat of compression to ignite the diesel fuel in the combustion chamber of the engine.
Many industrial applications where diesel engines are used would benefit environmentally and economically from use of natural gas as the engine fuel. Natural gas is generally readily available, tends to be more economical and produces less undesirable emissions when burned. Furthermore, engines burning natural gas generally have fewer maintenance problems. However, the ignition of natural gas in compression ignition engines is difficult because natural gas has a much higher temperature for auto ignition than diesel fuel. To resolve this problem a small amount of pilot fuel, such as diesel fuel, may be used to initiate ignition of the primary fuel, natural gas, in the combustion chamber of the engine. Such duel fuel engines require a duel fuel quill assembly injector feed that carries both the primary fuel and the pilot fuel to the engine. Because of the relative quantities and properties of the primary fuel and the pilot fuel, a duel fuel quill assembly injector feed must be used that can effectively provide the required sealing contact force at various junctures within the feed so that fuel leakage is minimized. In such engines a relatively small amount of pilot fuel is required and, as such, the quill tubes (of the duel fuel quill assembly) that carry the pilot fuel may be relatively smaller in diameter than the quill tubes the carry the primary fuel. Because of the size of the tubes and the properties of the fuels, typically a much higher pressure is required to seal flowpath junctures in a duel fuel quill assembly injector feed for the quill tubes carrying the primary fuel than for the quill tubes carrying the pilot fuel.
Canadian Patent 2,635,410 teaches a dual fuel connector that relies upon a single quill that includes two different internal passages to facilitate fluid connection to two different fuel inlets of a fuel injector. This type of dual fuel connector has drawbacks because, at a minimum, the reference fails to teach an effective strategy for inhibiting fuel leakage.
A design is needed for a duel fuel quill assembly that effectively seals the flowpaths for each fuel at the various junctures in the quill assembly over which each fuel must flow.